Flowers and fruits are the reproductive organs in plants that play essential role in nature beauty and human diet. CLAVATA signaling has been well characterized to regulate floral organ development through modulating shoot apical meristem (SAM) size, however, the signaling molecules downstream of CLV pathway remain largely unknown in crops. Here, we found that functional disruption of CsCLV3 peptide and its receptor CsCLV1 both resulted in flowers with extra organs and stumpy fruits in cucumber. A heterotrimeric G protein α-subunit (CsGPA1) was identified to interact with CsCLV1. Csgpa1 mutant plants derived from gene-editing displayed significantly increased floral organ numbers, shorter and wider fruits, a phenotype resembling of Csclv mutants in cucumber. Moreover, the SAM size was enlarged, and longitudinal cell size of fruit was decreased in Csgpa1 mutants. The expression of the classical stem cell regulator WUSCHEL (WUS) was elevated in the SAM, while the expression of the fruit length stimulator CRABS CLAW (CRC) was reduced in the fruit of Csgpa1 mutants. Therefore, the Gα-subunit CsGPA1 protein interacts with CsCLV1 to inhibit floral organ numbers but promote fruit elongation, via repressing CsWUS expression and activating CsCRC transcription in cucumber. Our findings identified a new player in the CLV signaling pathway during flower and fruit development in dicot, so that enrich target genes for precise manipulation of fruit shape during crop breeding.

中文翻译：

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异三聚体 Gα 亚基通过 CLAVATA 信号通路在黄瓜花和果实发育中发挥作用

花和果实是植物的生殖器官，在自然美景和人类饮食中发挥着重要作用。 CLAVATA 信号传导已被充分表征，可通过调节茎尖分生组织 (SAM) 大小来调节花器官发育，然而，CLV 途径下游的信号分子在作物中仍然很大程度上未知。在这里，我们发现 CsCLV3 肽及其受体 CsCLV1 的功能破坏都会导致黄瓜产生具有额外器官的花和短茎的果实。异源三聚体 G 蛋白 α 亚基 (CsGPA1) 被鉴定与 CsCLV1 相互作用。来自基因编辑的Csgpa1突变植物表现出显着增加的花器官数量、更短更宽的果实，其表型类似于黄瓜中的Csclv突变体。此外，Csgpa1 突变体的 SAM 尺寸增大，果实纵向细胞尺寸减小。经典干细胞调节因子 WUSCHEL (WUS) 的表达在 SAM 中升高，而果实长度刺激因子 CRABS CLAW (CRC) 的表达在 Csgpa1 突变体的果实中降低。因此，Gα 亚基 CsGPA1 蛋白与 CsCLV1 相互作用，通过抑制 CsWUS 表达并激活黄瓜中的 CsCRC 转录，抑制花器官数量，但促进果实伸长。我们的研究结果在双子叶植物花和果实发育过程中发现了 CLV 信号通路中的一个新参与者，从而丰富了作物育种过程中精确操纵果实形状的靶基因。